To see clearly, an image should focus directly on the retina  (the back of the eye). Astigmatism is when an image focuses in two different planes (either in front or behind the retina), causing the vision to be blurry at both distance and near. This occurs because of the shape of the eye, or focusing system is not completely spherical. Astigmatism can accompany myopia or hyperopia. This is corrected by toric lenses.